Cavegen: Rename CaveV6 to CavesV6

- Add comment explaining why it exists
- Remove unused 'flooded' variable
- Rename shadowed variable
- Fix some code style

src/cavegen.cpp

@@ -277,10 +277,12 @@ void CavesRandomWalk::carveRoute(v3f vec, float f, bool randomize_xz)
 }
 
 
-///////////////////////////////////////// Caves V6
+////
+//// CavesV6
+////
 
-
+CavesV6::CavesV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2,
-CaveV6::CaveV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2, bool is_large_cave)
+	bool is_large_cave)
 {
 	this->mg             = mg;
 	this->vm             = mg->vm;
@@ -295,7 +297,6 @@ CaveV6::CaveV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2, bool is_large_
 	min_tunnel_diameter = 2;
 	max_tunnel_diameter = ps->range(2, 6);
 	dswitchint          = ps->range(1, 14);
-	flooded             = true;
 
 	if (large_cave) {
 		part_max_length_rs  = ps->range(2, 4);
@@ -311,7 +312,7 @@ CaveV6::CaveV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2, bool is_large_
 }
 
 
-void CaveV6::makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height)
+void CavesV6::makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height)
 {
 	node_min = nmin;
 	node_max = nmax;
@@ -339,12 +340,12 @@ void CaveV6::makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height)
 	route_y_max = rangelim(route_y_max, 0, ar.Y - 1);
 
 	if (large_cave) {
-		s16 min = 0;
+		s16 minpos = 0;
 		if (node_min.Y < water_level && node_max.Y > water_level) {
-			min = water_level - max_tunnel_diameter/3 - of.Y;
+			minpos = water_level - max_tunnel_diameter / 3 - of.Y;
 			route_y_max = water_level + max_tunnel_diameter / 3 - of.Y;
 		}
-		route_y_min = ps->range(min, min + max_tunnel_diameter);
+		route_y_min = ps->range(minpos, minpos + max_tunnel_diameter);
 		route_y_min = rangelim(route_y_min, 0, route_y_max);
 	}
 
@@ -379,7 +380,7 @@ void CaveV6::makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height)
 }
 
 
-void CaveV6::makeTunnel(bool dirswitch)
+void CavesV6::makeTunnel(bool dirswitch)
 {
 	if (dirswitch && !large_cave) {
 		main_direction = v3f(
@@ -496,7 +497,8 @@ void CaveV6::makeTunnel(bool dirswitch)
 }
 
 
-void CaveV6::carveRoute(v3f vec, float f, bool randomize_xz, bool tunnel_above_ground)
+void CavesV6::carveRoute(v3f vec, float f, bool randomize_xz,
+	bool tunnel_above_ground)
 {
 	MapNode airnode(CONTENT_AIR);
 	MapNode waternode(c_water_source);
@@ -547,11 +549,10 @@ void CaveV6::carveRoute(v3f vec, float f, bool randomize_xz, bool tunnel_above_g
 					int full_ymin = node_min.Y - MAP_BLOCKSIZE;
 					int full_ymax = node_max.Y + MAP_BLOCKSIZE;
 
-					if (flooded && full_ymin < water_level &&
+					if (full_ymin < water_level && full_ymax > water_level) {
-							full_ymax > water_level) {
 						vm->m_data[i] = (p.Y <= water_level) ?
 							waternode : airnode;
-					} else if (flooded && full_ymax < water_level) {
+					} else if (full_ymax < water_level) {
 						vm->m_data[i] = (p.Y < startp.Y - 2) ?
 							lavanode : airnode;
 					} else {

src/cavegen.h

@@ -72,7 +72,20 @@ public:
 	void carveRoute(v3f vec, float f, bool randomize_xz);
 };
 
-class CaveV6 {
+/*
+	CavesV6 is the original version of caves used with Mapgen V6.
+
+	Though it uses the same fundamental algorithm as CavesRandomWalk, it is made
+	separate to preserve the exact sequence of PseudoRandom calls - any change
+	to this ordering results in the output being radically different.
+	Because caves in Mapgen V6 are responsible for a large portion of the basic
+	terrain shape, modifying this will break our contract of reverse
+	compatibility for a 'stable' mapgen such as V6.
+
+	tl;dr,
+	*** DO NOT TOUCH THIS CLASS UNLESS YOU KNOW WHAT YOU ARE DOING ***
+*/
+class CavesV6 {
 public:
 	MapgenV6 *mg;
 	MMVManip *vm;
@@ -86,7 +99,6 @@ public:
 
 	bool large_cave;
 	bool large_cave_is_flat;
-	bool flooded;
 
 	s16 max_stone_y;
 	v3s16 node_min;
@@ -109,8 +121,7 @@ public:
 
 	int water_level;
 
-	CaveV6() {}
+	CavesV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2, bool large_cave);
-	CaveV6(MapgenV6 *mg, PseudoRandom *ps, PseudoRandom *ps2, bool large_cave);
 	void makeCave(v3s16 nmin, v3s16 nmax, int max_stone_height);
 	void makeTunnel(bool dirswitch);
 	void carveRoute(v3f vec, float f, bool randomize_xz, bool tunnel_above_ground);

src/mapgen_v6.cpp

@@ -1067,7 +1067,7 @@ void MapgenV6::generateCaves(int max_stone_y)
 
 	for (u32 i = 0; i < caves_count + bruises_count; i++) {
 		bool large_cave = (i >= caves_count);
-		CaveV6 cave(this, &ps, &ps2, large_cave);
+		CavesV6 cave(this, &ps, &ps2, large_cave);
 
 		cave.makeCave(node_min, node_max, max_stone_y);
 	}